Tensile characteristics of flexible PU-coated multi-axial warp-knitted fabrics

Abstract

In practice, the coated fabric is available in many shapes and sizes, not just rectangle and plane. In order to increase the shape-shifting abilities of coated fabrics, polyurethanecoated multi-axial warp-knitted fabric (PU-CMWKF) is developed. In this paper, the tensile characteristics of PU-CMWKF were investigated. Five groups of tensile experiments, with off-axial angles of 0 , 22 , 45 , 67.5 , and 90 , were conducted under constant velocity. The failure mechanism was explored by analyzing the damaged specimens. Additionally, the deformation behavior of PU-CMWKF in three regions was investigated by utilizing the digital image correlation (DIC) system, and an orthogonal anisotropic model was used to predict the modulus and Poisson's ratio of 22.5 and 67.5 . Research results showed that the apparent modulus of PU-CMWKF strongly depended on the cut of directions. And the failure mechanism under in-plane direction loading suggests that tensile and shear failure act together. The analytical model is validated along five directions in the representation of elastic constant under corresponding small strain.

Strength characteristic and failure criterion of flexible multi-axial warp-knitted fabrics coated with polyurethane on single side

“…At present, the research on fabric-reinforced flexible composites is mainly focused on the mechanical properties and theory [6]. Kabche et al [3] studied the inter-tow contact interactions of inflatable membrane structure under different loading conditions and the effect of inflation pressure on the fabric stiffness.…”

Full-strain range characteristics of the Poisson’s ratio for coated biaxial warp-knitted fabrics under bias tensile loading

“…A survey of the literature shows that there are mainly two kinds of methods, namely the theoretical model 4,8,[12][13][14][15][16] and experimental methods, 7,8,[17][18][19][20][21][22] to estimate Poisson's ratios of fabric composites (most of them are woven fabrics). Using the theoretical model method, researchers 4,8,[12][13][14][15][16] have developed analytical models based on the previous classical models, such as the Peirce model, 12 or finite element models of fabric microstructures to reveal the Poisson effect, 4,13 calculate the apparent or real Poisson's ratios, 4,8,13,14 and analyze the influences of yarn properties or fabric structural parameters on Poisson's ratios.…”

“…Therefore, the experimental determination is a more reliable and effective method, 8,[17][18][19] which has been utilized in many recent investigations. 7,11,[20][21][22] Although the experimental method for determining the Poisson's ratios has been used by various authors, there still arise questions about the orientation-dependent characteristics of the Poisson's ratios and about the exact Poisson's ratios for specific stress (or strain) states and bias angles.…”

“…In addition, anisotropy is an important characteristic of most fabric composites, 20 especially for biaxial knitted and woven fabrics. 20,[22][23][24][25][26][27] The effects of the action direction of an external load on the fabric properties are enormous. [25][26][27] When the action direction of the external load changes, the elastic parameters, including the Poisson's ratios, 20,28 of the fabrics also vary, which is called the ''orientation dependence.''…”

“…[25][26][27] When the action direction of the external load changes, the elastic parameters, including the Poisson's ratios, 20,28 of the fabrics also vary, which is called the ''orientation dependence.'' Although the application of fabric composites in different industries is growing and many researchers 20,22,[25][26][27][28] have studied the anisotropic behaviors of fabric composites, the understanding of orientation dependence in the whole extension strain range of the fabric composites is still limited, especially for the BWKFs. Apparently, the lack of understanding of the orientation-dependent characteristics of fabric composites may hinder the utilization of the experimental results in the membrane structure designs, and there is an urgent need to investigate the orientation-dependent characteristics in full-strain range for reliable and precise structural designs.…”